From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sting Zax Subject: Re: frontend and backend devices and different types of hw - pci for example Date: Mon, 29 Aug 2005 02:57:07 -0400 Message-ID: <3a0f1c62050828235727cd55fa@mail.gmail.com> References: <3a0f1c6205082800287beb089@mail.gmail.com> <200508281625.09980.mark.williamson@cl.cam.ac.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <200508281625.09980.mark.williamson@cl.cam.ac.uk> Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Mark Williamson Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Hello,=20 I had looked at the code of 2.0.* under xen/arch/x86 saw=20 pci-irq.c and pci-pc.c and pci-x86.c which as I understand handle pci devic= es=20 other than net/usb. However, I did not saw such modules in the unstable version.=20 May I ask : is this PCI support for non net/usb PCI devices removed (or temporarily removed) from the unstable version? or maybe I simply missed it ? >Note that giving direct physical access to a PCI device has security >implications since the guest can potentially use the cards' DMA capabiliti= es >to access all of physical memory. =20 Will IOMMU support help solving this security problems ?=20 Regards, Sting On 8/28/05, Mark Williamson wrote: > > What about other devices ? let's say a PCI sound card (or any other PCI > > device). Where is the software that should handle it ? I remember I saw > > somewhere some discussion about PCI configuration space, but I don't > > remember where. >=20 > That code is in Xen itself in Xen 2.0. Xen controls access to the PCI > configuration spaces so that guests can only see the devices they have ac= cess > to. It also controls the IO memory / ports that domains are allowed to > access in order to control PCI devices. >=20 > Note that giving direct physical access to a PCI device has security > implications since the guest can potentially use the cards' DMA capabilit= ies > to access all of physical memory. The front/back-style devices do not ha= ve > this limitation. >=20 > Btw, I've laid some groundwork for a virtual sound device but haven't had= much > time to hack on it yet. >=20 > Cheers, > Mark >